The present invention relates to an apparatus for the insertion of a radially expandable shut-off device into a pipe portion via an auxiliary branch inclined at an obtuse angle to the pipe portion.
The problem of inserting such a shut-off device arises, in particular, when it is intended to repair or modify a pipe containing a fluid under pressure and when it is therefore necessary to isolate the pipe portion on which the operation will be carried out by means of shut-off devices according to the so-called "cold-tapping" technique. It may also be appropriate to insert a shut-off device in this way likewise in the so-called "hot-tapping" technique.
This problem is difficult to solve because the obtuse angle between the portion and the branch cannot be very large, usually approximately 135.degree. C., and because the radial movement of the shut-off device between its extended position and its retracted position is somewhat limited.